The present invention relates to straightening machines for deformable materials in general, and more particularly to a straightening machine for straightening sheet-shaped deformable materials during their advancement, as well as to a correspond ing straightening method.
There are already known various constructions of straightening machines for deformable materials, among them such in which a sheet or a band of such deformable material is introduced and advanced between an array of straightening rollers and an array of complementary rollers which alternate with one another as considered in a direction normal to their axes. In a machine of this construction, it is known to make the respective straightening roller flexible and to support the same on a plurality of support rollers which are distributed along the length of the straightening roller and are positionally adjustable beyond a support roller alignment plane or axis to deform the flexible straightening roller to the desired spatial configuration, so that the straightening roller correspondingly deforms the sheet-shaped material. The reason for providing and using such straightening machines is that, as is well known, planarity errors are encountered during or as a result of rolling, winding or cutting of bands and sheets of deformable materials, especially metallic materials. Such errors are, more often than not, unacceptable nowadays, especially in view of the constantly rising demands on the quality of the finished articles manufactured from such sheet-shaped materials, such as, for instance, decorative metal sheets, motor vehicle bodies or railroad car walls, and ship and airplane panels or walls.
In view of this, it has been known for some time to subject such bands, strips or sheets, for instance after their cutting from a coil, to a straightening operation or process, during which the planarity of such sheet-shaped materials is restored or achieved. During this process, both the developable (two-dimensional) and the non-developable (three-dimensional) curvatures are removed. Herein, the three-dimensional curvatures, which come into being most often during a rolling opperation as a result of different lengthening of the fibers of the band being rolled, require the greater mechanical straightening effort.
The straightening operation resides in that the straightening rollers (respectively the respective "straightening roller arrays" which are constituted by the straightening rollers arranged downstream from one another) are immersed or introduced over their effective lengths, which must amount to somewhat more than the width of the deformable sheet material to be straightened to different extents between the complementary rollers. In this manner, the material being straightened is stretched at the regions of increased immersion depth of the straightening rollers with respect to the material fibers parallel thereto at the regions of lesser immersion depth. It is thus achieved in this manner that the material fiber lengths are equalized with one another.
In order to obtain different immersion depths between the complementary rollers over the effective lengths of the respective straightening rollers, the straightening rollers must be elastically deformed. Thus, it has already been proposed to utilize support rollers which support the respective straightening roller at longitudinally spaced regions of the latter for this purpose. The support rollers are separate from one another and are distributed over the effective length of the straightening roller. Depending on the width of the material to be straightened, between 3 and about 13 or even more of such support rollers are used for each of the straightening rollers. The support rollers then supporr the respective straightening roller against the forces exerted on the latter by the material being straightened.
When all of the support rollers are aligned with one another, that is, when they lie along a support roller alignment axis or plane and their axes coincide therewith, such axis or plane being tangential to the straightening roller and to the support rollers at their region of contact, then even the straightening roller is straight. On the other hand, when the position of one of the support rollers is elevated or displaced beyond the support roller alignment plane, then the flexible straightening roller is, as expected, elastically bent or deformed and in this manner the immersion depth of the straightening roller at this region between the complementary rollers is correspondingly increased with attendant stretching of the material being straightened at the corresponding fiber.
A considerable disadvantage of known straightening arrangements and associated methods of this kind results from the fact that positional adjustment not only of the respective determinative support roller, that is, the support roller whose position is selectively adjusted in order to achieve the desired straightening effect, but also of the remaining neighboring support rollers associated with the same straightening roller, must be accomplished during the operation of the straightening machine. The criterion for the positional adjustment and the positional readjust ment of the predeterminative support roller, on the one hand, and of the remaining support rollers, on the other hand, is the "best straightening result" in the material being straightened.
Each of these adjustment operations requires a relatively huge length of the material being straightened. Thus, when the predeterminative support roller is positionally adjusted first after the required immersion depth thereof has been determined, and then the needed immersion depths of the remaining support rollers are established and readjustment of such rollers is performed, the the material being straightened that has been "used" so far cannot be straightened by utilizing the finally found adjustment, inasmuch as the straightening conditions precisely for this sheet-shaped material have completely changed in the meantime.